#!/usr/bin/env pytest
###############################################################################
#
# Project:  GDAL/OGR Test Suite
# Purpose:  Test overviews support in VRT driver
# Author:   Even Rouault <even dot rouault at spatialys.com>
#
###############################################################################
# Copyright (c) 2010, 2020, Even Rouault <even dot rouault at spatialys.com>
#
# SPDX-License-Identifier: MIT
###############################################################################

import struct

import gdaltest
import pytest

from osgeo import gdal

pytestmark = pytest.mark.skipif(
    not gdaltest.vrt_has_open_support(),
    reason="VRT driver open missing",
)

###############################################################################
# Simple test


def test_vrtovr_1():

    vrt_string = """<VRTDataset rasterXSize="20" rasterYSize="20">
  <VRTRasterBand dataType="Byte" band="1">
    <ColorInterp>Gray</ColorInterp>
    <SimpleSource>
      <SourceFilename relativeToVRT="0">data/byte.tif</SourceFilename>
      <SourceBand>1</SourceBand>
      <SourceProperties RasterXSize="20" RasterYSize="20" DataType="Byte" BlockXSize="20" BlockYSize="20" />
      <SrcRect xOff="0" yOff="0" xSize="20" ySize="20" />
      <DstRect xOff="0" yOff="0" xSize="20" ySize="20" />
    </SimpleSource>
    <Overview>
      <SourceFilename relativeToVRT="0">data/int16.tif</SourceFilename>
      <SourceBand>1</SourceBand>
    </Overview>
  </VRTRasterBand>
</VRTDataset>"""

    ds = gdal.Open(vrt_string)
    assert (
        ds.GetRasterBand(1).GetOverviewCount() == 1
    ), "did not get expected overview count"

    cs = ds.GetRasterBand(1).GetOverview(0).Checksum()
    assert cs == 4672, "did not get expected overview checksum"

    fl = ds.GetFileList()
    assert fl == ["data/byte.tif", "data/int16.tif"], "did not get expected file list"

    ds = None


###############################################################################
# Test serialization


def test_vrtovr_2():

    vrt_string = """<VRTDataset rasterXSize="20" rasterYSize="20">
  <VRTRasterBand dataType="Byte" band="1">
    <ColorInterp>Gray</ColorInterp>
    <SimpleSource>
      <SourceFilename relativeToVRT="0">data/byte.tif</SourceFilename>
      <SourceBand>1</SourceBand>
      <SourceProperties RasterXSize="20" RasterYSize="20" DataType="Byte" BlockXSize="20" BlockYSize="20" />
      <SrcRect xOff="0" yOff="0" xSize="20" ySize="20" />
      <DstRect xOff="0" yOff="0" xSize="20" ySize="20" />
    </SimpleSource>
    <Overview>
      <SourceFilename relativeToVRT="0">data/byte.tif</SourceFilename>
      <SourceBand>1</SourceBand>
    </Overview>
  </VRTRasterBand>
</VRTDataset>"""

    f = gdal.VSIFOpenL("/vsimem/vrtovr_2.vrt", "wb")
    gdal.VSIFWriteL(vrt_string, len(vrt_string), 1, f)
    gdal.VSIFCloseL(f)

    ds = gdal.Open("/vsimem/vrtovr_2.vrt", gdal.GA_Update)
    ds.GetRasterBand(1).SetDescription("foo")
    ds = None

    ds = gdal.Open("/vsimem/vrtovr_2.vrt")
    assert (
        ds.GetRasterBand(1).GetOverviewCount() == 1
    ), "did not get expected overview count"

    cs = ds.GetRasterBand(1).GetOverview(0).Checksum()
    assert cs == 4672, "did not get expected overview checksum"

    ds = None

    gdal.Unlink("/vsimem/vrtovr_2.vrt")


###############################################################################
#


def test_vrtovr_none():

    vrt_string = """<VRTDataset rasterXSize="20" rasterYSize="20">
  <VRTRasterBand dataType="Byte" band="1">
    <ColorInterp>Gray</ColorInterp>
    <SimpleSource>
      <SourceFilename relativeToVRT="0">data/byte.tif</SourceFilename>
      <SourceBand>1</SourceBand>
      <SourceProperties RasterXSize="20" RasterYSize="20" DataType="Byte" BlockXSize="20" BlockYSize="20" />
      <SrcRect xOff="0" yOff="0" xSize="20" ySize="20" />
      <DstRect xOff="0" yOff="0" xSize="20" ySize="20" />
    </SimpleSource>
  </VRTRasterBand>
</VRTDataset>"""

    ds = gdal.Open(vrt_string)
    assert (
        ds.GetRasterBand(1).GetOverviewCount() == 0
    ), "did not get expected overview count"

    assert not ds.GetRasterBand(1).GetOverview(0)


###############################################################################
#


def test_vrtovr_errors():

    vrt_string = """<VRTDataset rasterXSize="20" rasterYSize="20">
  <VRTRasterBand dataType="Byte" band="1">
    <ColorInterp>Gray</ColorInterp>
    <SimpleSource>
      <SourceFilename relativeToVRT="0">data/byte.tif</SourceFilename>
      <SourceBand>1</SourceBand>
      <SourceProperties RasterXSize="20" RasterYSize="20" DataType="Byte" BlockXSize="20" BlockYSize="20" />
      <SrcRect xOff="0" yOff="0" xSize="20" ySize="20" />
      <DstRect xOff="0" yOff="0" xSize="20" ySize="20" />
    </SimpleSource>
    <Overview>
      <SourceFilename relativeToVRT="0">data/int16.tif</SourceFilename>
      <SourceBand>123456</SourceBand>
    </Overview>
  </VRTRasterBand>
</VRTDataset>"""

    ds = gdal.Open(vrt_string)
    assert (
        ds.GetRasterBand(1).GetOverviewCount() == 1
    ), "did not get expected overview count"

    assert not ds.GetRasterBand(1).GetOverview(-1)

    assert not ds.GetRasterBand(1).GetOverview(1)

    with pytest.raises(Exception):
        assert not ds.GetRasterBand(1).GetOverview(0)


###############################################################################
# Test support for virtual overviews


def test_vrtovr_virtual():

    tif_tmpfilename = "/vsimem/temp.tif"
    src_ds = gdal.GetDriverByName("GTiff").Create(tif_tmpfilename, 20, 20, 3)
    src_ds.BuildOverviews("NEAR", [2, 4])
    src_ds.GetRasterBand(1).Fill(200)
    src_ds.GetRasterBand(2).Fill(100)
    src_ds.GetRasterBand(1).GetOverview(0).Fill(100)
    src_ds.GetRasterBand(1).GetOverview(1).Fill(50)
    src_ds = None
    src_ds = gdal.Open(tif_tmpfilename)

    tmpfilename = "/vsimem/temp.vrt"
    vrt_ds = gdal.Translate(tmpfilename, src_ds, format="VRT")
    assert (
        vrt_ds.GetRasterBand(1).GetOverviewCount() == 0
    )  # we normally don't create implicit overviews on that small datasets

    with gdaltest.config_option("VRT_VIRTUAL_OVERVIEWS", "YES"):
        vrt_ds.BuildOverviews("NEAR", [2, 4, 5, 50])  # level 50 is too big
    assert gdal.VSIStatL(tmpfilename + ".ovr") is None
    assert vrt_ds.GetRasterBand(1).GetOverviewCount() == 3

    # Clean overviews
    with gdaltest.config_option("VRT_VIRTUAL_OVERVIEWS", "YES"):
        vrt_ds.BuildOverviews("NONE", [])
    assert vrt_ds.GetRasterBand(1).GetOverviewCount() == 0

    # Add in two steps
    with gdaltest.config_option("VRT_VIRTUAL_OVERVIEWS", "YES"):
        vrt_ds.BuildOverviews("NEAR", [2, 4])
        vrt_ds.BuildOverviews("NEAR", [5])
    assert vrt_ds.GetRasterBand(1).GetOverviewCount() == 3

    assert (
        vrt_ds.GetRasterBand(1).GetOverview(0).Checksum()
        == src_ds.GetRasterBand(1).GetOverview(0).Checksum()
    )
    assert (
        vrt_ds.GetRasterBand(1).GetOverview(1).Checksum()
        == src_ds.GetRasterBand(1).GetOverview(1).Checksum()
    )
    assert vrt_ds.ReadRaster(0, 0, 20, 20, 10, 10) == src_ds.ReadRaster(
        0, 0, 20, 20, 10, 10
    )
    assert vrt_ds.GetRasterBand(1).ReadRaster(
        0, 0, 20, 20, 10, 10
    ) == src_ds.GetRasterBand(1).ReadRaster(0, 0, 20, 20, 10, 10)
    assert vrt_ds.GetRasterBand(1).ReadRaster(
        0, 0, 20, 20, 5, 5
    ) == src_ds.GetRasterBand(1).ReadRaster(0, 0, 20, 20, 5, 5)
    assert (
        struct.unpack(
            "B" * 4 * 4, vrt_ds.GetRasterBand(1).ReadRaster(0, 0, 20, 20, 4, 4)
        )[0]
        == 50
    )
    vrt_ds = None

    # Re-open VRT and re-run checks
    vrt_ds = gdal.Open(tmpfilename)
    assert vrt_ds.GetRasterBand(1).GetOverviewCount() == 3
    assert (
        vrt_ds.GetRasterBand(1).GetOverview(0).Checksum()
        == src_ds.GetRasterBand(1).GetOverview(0).Checksum()
    )
    assert (
        vrt_ds.GetRasterBand(1).GetOverview(1).Checksum()
        == src_ds.GetRasterBand(1).GetOverview(1).Checksum()
    )
    assert vrt_ds.ReadRaster(0, 0, 20, 20, 10, 10) == src_ds.ReadRaster(
        0, 0, 20, 20, 10, 10
    )
    assert vrt_ds.GetRasterBand(1).ReadRaster(
        0, 0, 20, 20, 10, 10
    ) == src_ds.GetRasterBand(1).ReadRaster(0, 0, 20, 20, 10, 10)
    assert vrt_ds.GetRasterBand(1).ReadRaster(
        0, 0, 20, 20, 5, 5
    ) == src_ds.GetRasterBand(1).ReadRaster(0, 0, 20, 20, 5, 5)
    assert (
        struct.unpack(
            "B" * 4 * 4, vrt_ds.GetRasterBand(1).ReadRaster(0, 0, 20, 20, 4, 4)
        )[0]
        == 50
    )

    gdal.Unlink(tmpfilename)
    gdal.Unlink(tif_tmpfilename)


###############################################################################
# Test support for virtual overviews, when there are pre-existing implicit
# overviews


def test_vrtovr_virtual_with_preexisting_implicit_ovr():

    src_ds = gdal.GetDriverByName("MEM").Create("", 1000, 1000)
    src_ds.BuildOverviews("NEAR", [2])
    vrt_ds = gdal.Translate("", src_ds, format="VRT")
    assert vrt_ds.GetRasterBand(1).GetOverviewCount() == 1

    with gdaltest.config_option("VRT_VIRTUAL_OVERVIEWS", "YES"):
        vrt_ds.BuildOverviews("NEAR", [2, 4])
    assert vrt_ds.GetRasterBand(1).GetOverviewCount() == 2


###############################################################################
# Test support for virtual overviews, when there are pre-existing implicit
# overviews


def test_vrtovr_external_ovr_has_priority_over_implicit():

    src_ds = gdal.GetDriverByName("GTiff").Create("/vsimem/in.tif", 100, 100)
    src_ds.GetRasterBand(1).Fill(255)
    vrt_ds = gdal.Translate("/vsimem/test.vrt", src_ds, format="VRT")
    src_ds = None
    with gdaltest.config_option("VRT_VIRTUAL_OVERVIEWS", "YES"):
        vrt_ds.BuildOverviews("NEAR", [2, 4])
    assert vrt_ds.GetRasterBand(1).GetOverviewCount() == 2
    vrt_ds = None

    vrt_ds = gdal.Open("/vsimem/test.vrt")
    assert vrt_ds.GetRasterBand(1).GetOverviewCount() == 2
    assert vrt_ds.GetRasterBand(1).GetOverview(0).Checksum() != 0
    # Build external overviews
    vrt_ds.BuildOverviews("NONE", [2])
    vrt_ds = None

    # Check that external overviews has the priority
    vrt_ds = gdal.Open("/vsimem/test.vrt")
    assert vrt_ds.GetRasterBand(1).GetOverviewCount() == 1
    assert vrt_ds.GetRasterBand(1).GetOverview(0).Checksum() == 0
    vrt_ds = None

    gdal.GetDriverByName("GTiff").Delete("/vsimem/in.tif")
    gdal.Unlink("/vsimem/test.vrt")


###############################################################################
# Cleanup.


def test_vrtovr_cleanup():
    pass
